| Objectives Aortic dissection is a serious cardiovascular disease that threatens human life and health,the incidence of the disease is urgent,dangerous and heavy,and its incidence is increasing year by year,this has attracted the attention of researchers at home and abroad,so the disease is an urgent need to further research and understanding,but its pathogenesis has not been fully elucidated.This project is based on the analysis of clinical samples,animal experiments and cell experiments,focus on the biomechanical properties and the abnormal expression of micro RNA-224 of vascular wall,in-depth study the mechanism and intervention strategies of aortic dissection,It provides scientific basis for the study of the occurrence and development of aortic dissection from the aspects of gene and biomechanics,at the same time,this study may provide new targets and strategies for early diagnosis,prevention and treatment of aortic dissection.Methods We found that mi R-224 has a role in the regulation of a variety of genes and proteins related to aortic wall mechanics through bioinformatics search,so mi R-224 has been selected as the research target and hopes to verify the relationship between the changes of biomechanical properties and the mi R-224 expression of the aortic wall.First,under the premise of ethical review and informed consent of patients,6 cases of aortic wall were collected from normal donors and aortic dissection patients respectively;The total RNA was extracted from all aortic tissue samples according to the standard procedure,q RT-PCR was used to detect the expression of mi R-224;Then,the aortic tissue was finely cut to a dumbbell shape about 15 mm long,and the uniaxial tensile tests were carried out to obtain the stress-strain curve,ultimate stress and ultimate strain,the relationship between the expression of mi R-224 and the mechanical properties of aortic wall was compared;To further study the changes of biomechanical properties of aortic wall after mi R-224 intervention,we create aortic dissection model using FVB mice and intervention the expression of mi R-224 of mice through inject mi R-224 agomir/antagomir through tail vein of the mice.The blank control group,normal model group,mi R-224 up expreppion group,mi R-224 up expreppion control group,mi R-224 down expreppion group and mi R-224 down expreppion control group were respectively set up,to invesgate the effect of mi R-224 on vascular remodeling and biomechanical properties of the aortic wall.In the end of the experiment,mice were killed and dissected mouse aorta,and gross anatomy observation lesions of aortic dissection,the mouse aorta was divided into 4 sections,4% paraformaldehyde fixed paraffin sections,HE staining to measure mouse aortic wall thickness;comparison the content of elastic fibers in EVG staining and collagen fibers in Masson staining of mouse aortic,the expression level of mi R-224 was verified by q RT-PCR;Changes of mechanical related proteins Rho,ROCK1,SMAD expression was detected by immunohistochemical method in mechanics,Using Electroforce 5500 test the mechanical proterty of mice aortic wall in uniaxial tensile test,record and compare the stress,strain and ultimate stress,ultimate strain,to obtain the stress-strain curve calculation of elastic modulus and stiffness and other mechanical parameters.The change of elastic modulus under different strain conditions was analyzed by linear fitting,the AUC was calculated,and the effects of mi R-224 on the mechanical properties of the aortic wall were studied,verify the changes of mechanical properties of aorta wall after the intervention of mi R-224 expression..Results Clinical sample study,We found that the expression of mi R-224 in aortic dissection patients was significantly up-regulated in patients with aortic dissection(P<0.05);The uniaxial tensile tests were performed on aortic tissue of aortic dissection and normal donors,the results show that compared with the normal group,the ultimate load,ultimate displacement,ultimate stress and the ultimate strain of the aortic dissection group were significantly reduced(P<0.05),the initial elastic modulus of the aortic dissection group was significantly lower than that of the normal group(P<0.01),however there was no significant difference between the two groups of maxl elastic module(P>0.05).Animal experimental results were as follows: the incidence of aortic dissection after modeling,control(n=0/11,0),module(5/12,41.67%),mi R-224 down regulation(3/12,25%),mi R-224 down regulation contron(4/12,33.32%),mi R-224 up regulation(6/11,54.54%),mi R-224 up regulation control(5/11,45.45%),statistical analysis showed that the incidence of aortic dissection in mi R-224 up regulation group increased significantly compared with the normal module group(6/11 vs 5/12,P<0.01),the incidence of aortic dissection in mi R-224 down regulated group was significantly lower than that in module group((3/12 vs 5/12,P,<0.01);The results of q RT-PCR showed that mir-224 agomir could significantly promote the expression of mi R-224 in the aorta of mice mir-224 antagomir could significantly inhibit the expression of mi R-224 in aorta(P<0.05);The results of mechanical tests on the aortic wall of mice: compared with the blank control group,the thickness of the aortic wall of the rest groups was significantly increased(P<0.05)and same to the up regulation group vs down regulation group(P<0.05),compare to the up regulation group down regulation group could significantly increase aortic mechanical properties of aortic wall(P<0.05),however,there was no significant difference in the limit displacement and the tensile ratio between the two groups(P>0.05).EVG staining analysis showed that,compared with the control group mi R-224 up regulation group the elastic fibers of mice aortic tend to decreased,structural disorder,and even rupture;Masson staining showed that mi R-224 down-regulation could increase the content of aortic elastic fibers and collagen fibers in mice,which indicated that down-regulation of mi R-224 may play a protective role in the formation of aortic dissection;The results of immunohistochemistry showed that compared to the control group the expression of Rho/ROCK1 and SMAD in mi R-224 up regulation group are obvious.Conclusions We investigated the relationship between the expression of mi R-224 and the biomechanical properties of the aortic wall for the first time,the relationship between mir-224 expression and aortic dissection was clarified,the biomechanical property of human thoracic aorta was investigated through mechanical mechine,we found that mi R-224 was highly expressed in patients with aortic dissection,Accord with this the mechanical property of aortic dissection tissue was reduced.Further animal experiments results show that the incidence of aortic dissection was significantly increased after the up regulation intervention of mi R-224,while the mi R-224 down regulation group on the contrary,the results suggest that mi R-224 is a contributing factor for the occurrence of aortic dissection,mi R-224 up regulation can significantly reduce the ultimate stress,ultimate strain,initial elastic modulus,AUC and so on,reduce the content of elastic fibers and collagen fibers,further more immunohistochemical results suggest that it may play a role through Rho\\ROCK1 and SMAD pathway,thus,further lead to the occurrence and development of aortic dissection,this study will provide a new target and direction for the early diagnosis,prevention and treatment of aortic dissection... |
PDF Full Text Request